Work during this project period will focus on a physiological analysis of the nervous control of specified eye muscles in the blind cave crayfish, Procambarus erythrops. We will look specifically for 1) reflexes in which these muscles are involved and 2) the number, response properties, and nucleus of origin of motor axons innervating the muscles. A comparative study of eye muscle fine structure will also be undertaken. Cave crayfish eye muscles are smaller than their homologues in epigean species. Is the size reduction a function of fewer muscle fibers, smaller muscle fibers, or both? Finally, we will continue with an electrophysiological and anatomical analysis of two giant neurons in the crayfish brain which control withdrawal reflexes of the compound eyes. BIBLIOGRAPHIC REFERENCES: Mellon, DeF., Tufty, R.M., Lorton, E.D. Analysis of spatial constancy of oculomotor neurons in the crayfish. Brain Res. 109,587-594 (1976). Mellon, DeF. Central and peripheral features of crayfish oculomotor organization. In Identified Neurons and Arthropod Behavior (Ed. Hoyle) 1977, in press, Plenum Press.